Protocols for Secure Communication in Wireless Sensor Networks

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often ad hoc and transient nature of communication relationships. Thus, novel
mechanisms are required that provide a sufficient level of security while respecting
the constraints in wireless sensor networks.
Our thesis is that key pre-distribution is an appropriate technique for secret
key agreement in wireless sensor networks, and that based on locally shared
keys, multi-hop communication can be adequately protected using an interleaved
message authentication scheme.
We argue that combined key pre-distribution schemes provide a feasible
mechanism for key agreement in wireless sensor networks. They require only
simple operations on sensor nodes and their memory requirements can be adapted
to the required security level and the available resources. Based on keys
shared between nodes within a k-hop neighbourhood (with small k), a message
authentication scheme is devised that allows for the secure transmission
of messages over long distances. In particular, our contributions are:
• A key establishment scheme for pairwise key agreement that can be efficiently
implemented on resource-constrained wireless sensor nodes and
provides resilience against node capture attacks.
• A message authentication scheme that relies on locally shared keys and
symmetric cryptographic operations only, and provides a level of security
approximating that of end-to-end security mechanisms. The foundation
of the scheme’s security is the creation of multiple disjoint authentication
paths.
• An evaluation of this authentication scheme showing that it provides at
least the same security level as a general communication scheme that relies
on multiple disjoint physical paths.
The proposed security mechanisms protect the integrity of messages that are
exchanged within a wireless sensor network. The achievable level of security is,
given an attacker with moderate strength that is only able to capture a fraction
of all nodes, comparable to that provided by end-to-end security mechanisms
at a significantly lower cost in terms of computational resources.